Motor vehicle plunger type switch unit with self-adjusting shaft coupling connection

ABSTRACT

A self-adjusting start inhibitor switch unit for installation on motor vehicles equipped with transmissions is disclosed. The switch unit alternatively allows for actuation of the vehicle&#39;&#39;s engine starting circuit or completes the circuit to light the vehicle&#39;&#39;s reverse lamps or does neither depending upon the axial displacement of a spool which is moved by a plunger which rides on a cam surface that responds to the transmission shift lever setting. A locking washer connection between the plunger and spool allows the plunger to automatically and inversetelescopically adjust to the correct arrangement as the switch unit is attached to the transmission housing or other seating and thus allows for a greater range of tolerances in the switch unit&#39;&#39;s housing, the transmission housing and the use of less labor in affixing the switch unit.

United States Patent [1 1 Schumacher [ll] 3,710,048 [451 Jan. 9, 1973[541 MOTOR VEHICLE PLUNGER TYPE SWITCH UNIT WITH SELF-ADJUSTING SHAFTCOUPLING CONNECTION [75] Inventor: Cecil W. Schumacher, Letchworth,

England [73] Assignee: Borg-Warner Limited, Letchworth,

England [22] Filed: June 28, 1971 [21] Appl. No.: 157,523

[30] Foreign Application Priority Data Sept. 24, 1970 Great Britain..45,634/70 [52] US. Cl. ..200/52 R, 64/15 B 200/16 B, 200/17 R,200/6l.81, ZOO/61.89

[51] Int. Cl. ..HOlh 3/14, HOlh 3/38 [58] Field of Search ..200/16, 52R, 61.89, 159 R, 200/153 LB; 64/15 B; 85/36, 50 R [56] References CitedUNITED STATES PATENTS 3,251,956 5/1966 Rasor et al ..200/153 LB X3,105,884 10/1963 Cottrell ..200/61.89

W l lli I. t s

3,007,726 11/1961 Parkin ..85/36 X 3,272,929 9/1966 Hacker ....200/l6 BX 2,100,232 ll/l937 Barry ..64/15 B 3,428,842 2/1969 Harris ..85/50 R X2,621,947 12/1952 Markvart ..85/36 X Primary ExaminerJ. R. ScottAttorney-Richard G. Kinney [57] ABSTRACT A self-adjusting startinhibitor switch unit for installation on motor vehicles equipped withtransmissions is disclosed. The switch unit alternatively allows foractuation of the vehicles engine starting circuit or completes thecircuit to light the vehicles reverse lamps or does neither dependingupon the axial displacement of a spool which is moved by a plunger 7which rides on a cam surface that responds to the transmission shiftlever setting. A locking washer connection between the plunger and spoolallows the plunger to automatically and inverse-telescopically adjust tothe correct arrangement as the switch unit is attached to thetransmission housing or other seating and thus allows for a greaterrange of tolerances in the switch units housing, the transmissionhousing and the use of less labor in affixing the switch unit.

11 Claims, 9 Drawing Figures MOTOR VEHICLE PLUNGER TYPE SWITCH UNIT WITHSELF-ADJUSTING SHAFT COUPLING CONNECTION FIELD OF THE INVENTION Thepresent invention is directed to an improved switch unit of the typethat is used to inhibit engine startingof vehicles when theirtransmissions are conditioned to transmit propelling power.

BACKGROUND OF THE INVENTION Inhibitor switch units, which are alsotermed neutral switch units, have been employed in motor vehicles havingautomatic transmissions to prevent starting or attempts to start theengine when the engine is coupled through the transmission to propel thevehicle. For example, reference could be had to the switch unitdisclosed in U.S. Pat. No. 3,242,280, entitled Transmission NeutralSwitch and issued in the name of LaV. M. Krieger. Such switch units areconventionally affixed to the transmission housing as shown in thatpatent, or coupled to the transmission itself or else positionedadjacent to the selector level mechanism or other selector unit.

It is the present practice with some commercial automobile inhibitorswitch units to achieve the proper spacial relationship between theswitch actuating member and the switch unit during assembly by allowingfor a range of positions for the unit and, by trial and-error and humanobservation, adjusting the unit's position until it operates properlyand then permanently affixing the unit in that place.

As recognized in the Krieger patent and also in U.S. Pat. No. 3,423,549entitled Vehicle Safety Control Apparatus Having a Self-Adjusting Switchwhich issued in the name of R. M. Sondej, it is desirable to allow forvariations or vmanufacturing tolerances between the switch actuatingmember and the housing to which the switch unit is affixed.

While the schemes of the aforementioned Krieger and Sondej patents allowfor tolerance build-up they do it by providing an additional moving partsurrounding the main switch actuating plunger which moving part ismechanically biased against theactuating member. This biasing producesan additional drag or frictional resistance to movement and requires acorrespondingly greater force to displace the plunger and results ingreater wear on the parts. Moreover, as the degree of misplacementincreases, the mechanical bias increases closed in the environment oftransmission oil. Unavoidable sparking across the contact points in theenvironment of transmission oil is undesirable as it may result inincreased contact corrosion and fouling and, in the case of'comtaminated oil, possible short-circuitmg.

SUMMARY OF THE INVENTION In overcoming one or more of the abovedisadvantages of prior art inhibitor switch units the present inventionprovides such a switch unit in which the plunger and an internal contactsleeve or spool are connected to allow telescopic motion therebetweeninresponse to a force greater than that normally exerted in closing, soas to adjust automatically during the initial seating of the unit intoits operational position. This leaves only one unit, the interlockedspool and plunger, to move in response to the switch actuating member.

Because the adjustment takes place internally the electrical contactsurfaces are easily sealed from the transmission fluid by providing asealing ring between the plunger and its housings. This eliminatesproblems of contact fouling or shorting caused by transmission oil.

As each plunger is precisely aligned with the switch acting member afterinstallation the pressure and wear will be essentially the same for allswitch units in a production run, despitetolerance build-ups andvariations between individual housings and seatings.

BRIEF DESCRIPTION OF THE DRAWINGS The features of the present inventionwhich are believed to be novel are set forth with particularity in theappended claims. The invention, together with the further advantagesthereof, may best be understood by reference to the followingdescription taken in connec tion with the accompanying drawings, in theseveral figures of which like reference numerals identify like elements,and in which: I

FIG. 1 is a perspective view of one embodiment of a start inhibitorswitch unit constructed in accordance with the present invention;

FIG. 2 is a longitudinal sectional view of the switch unit of FIG. 1installed in a transmission; which transmission is shown partly insection and partly broken away;

FIG. 3 is a longitudinal sectional view of the switch unit of FIGS. 1and 2, as seen from the line 3-3 in FIG. 2 with certain parts in a movedposition;

FIG. 4 is a perspective view of a locking washer forming a part of theswitch unit of FIGS. 1-3;

FIGS. 5-8 are simplified longitudinal sectional views similar to that ofFIG. 2 of the switch unit of FIGS. 1-3, showing progressive stages ofmounting the switch unit in a transmission, and useful therefore inillustrating the relationships between the internal switch units partsat various stages of installation; and

FIG. 9 is a sectional view of the switch unit as seen from the line 9-9in FIG. 2.

DETAILED DESCRIPTION Referring to FIG. 1, there is depicted a vehicletransmission switch unit constructed in accordance with the presentinvention which is generally designated by the numeral 10. The switchunit 10 includes a body or case 12 having a threaded cylindrical frontend section 14 projecting from a stop shoulder 16. Projecting from thecenter of the threaded section 14 of the case 12 is a plunger 18. At theoppositeend of the switch unit 10 is an insulating base 20 from whichfour electrical terminals 21, 22, 23 and 24 extend. The terminal pair21,

22 are for connection to control the reverse indicating or warning lampsof a vehicle while the terminal pair 23, 24 is for connection in serieswith the vehicle engine starting circuit. The axial displacement of theplunger 18 alternatively either completes a current path between onlythe terminals 21, 22 or completes a circuit path only between theterminals 23, 24 or completes no current path between any of theterminals 21-24.

As better seen in FIG. 2, the plunger 18 extends through a cylindricalbore 128 into a closed zone 19 enclosed by the body 12 and base 20.Within the case 12, the plunger 18 is coupled to a generally cylindricaland electrically insulating sleeve or spool 26 which has an encirclinggenerally annular groove 28 formed about its outer cylindrical surfaceto receive a conducting ring 30. The terminals 21 and 22 areelectrically connected through the insulating base 20 to respective lyswitch contacts 31, 32 which are mechanically biased to bear resilientlyagainst the outer cylindrical surface of the spool 26. As also shown inFIG. 2, when the plunger 18 is moved inward to move the spool 26 to itsextreme rearward position the contacts 31 and 32 bear against the ring30 to complete a current path between the terminals 21 and 22 thus.making the electrical contact between these contacts. This current pathincludes a pair of rivets 51 and 52 which pass through the base 20 toboth physically secure and electrically connect the terminals andcontacts. It should be noted that the outer surface of the ring 30 isflush with the cylindrical surface of the spool 26 to allow smoothrelative movement between the ring 30 and the contact points 31, 32.

The spool 26 and its coupled plunger 18 are mechanically biased bymeansof a helical spring 36 toward the threaded end 14 (to the right asseen in FIG. 2). The spool 26 has a limited range of positions betweenthat shown in FIG. 2 in which its rearward edge, designated 26Y, makescontact with a stop surface 20X formed on the forward facing surface ofthe base 20.and its extreme forward position shown in FIG. 3. As thespool 26 moves forward it breaks the contact made between the contactpoints 31, 32.

As depicted in FIG. 3, the terminals 23, 24 can be seen to beelectrically connected to internal switch contacts 33, 34 respectively.These contacts 33, 34 are constructed similarly to the contacts 31, 32but bear against the spool surface at a place forward of the point ofbearing of those contacts 31, 32. The orientation of the contacts 31,32, 33 and 34 about the axis of the spool 26 is shown in FIG. 9. As canbe there seen, these 'contacts 31-34 remain electrically isolated fromone another. With the spool 26 at the extreme forward position, asdepicted in FIG. 3, an electrical contact is made, i.e. a current pathis created between the terminals 23 and 24 through respective connectingrivets 53, 54, the contacts 33, 34 and the ring 30. This secondelectrical contact is broken when the plunger 18 moves the ring holdingspool 26 back toward the surface 20X.

The switch unit 10 ispreferably employed physically mounted through atransmission case and also includes, as can be seen from FIGS. 2 and 3,a sealing O-ring 17 seated in a groove in the plunger 18. The O-ring 17is positioned in a part of the plunger 18 that always (in use) makescontact with the bore 128 so as to seal the zone 19 from thetransmission case environment.

A second O-ring 27 is also preferably provided to seal the junctionbetween the body 12 and base'20. The

zone 19 is thus preferably enclosed and sealed against both road grimeand water from the outside of the transmission housing and againsttransmission fluid and any contaminants thereof from the inside of thetransmission housing.

FIGS. 2 and 3 also depict, in part, the transmission which is generallydesignated 60 and includes a housing 62 through which a female threadedopening 64 is formed to receive the self-locking threaded portion 14 ofthe switch unit 10.

Within the transmission housing, as is conventional, is provided,adjacent to the switch unit receiving tapped opening 64, a cam 54 havinga cam surface 56 which includes a low portion 58 and a high portion 59.When the transmission 60 is in park, or (if so designed) in neutral",the cam is positioned as shown in FIG. 2 with the surface 59 oppositethe opening 64. When the shift lever is moved to place the transmission60 in reverse" the low surface 58 is moved (as shown in FIG. 2) to beopposite the opening 64. Intermediate surface depths are provided forthe forward drive gears. It is generally considered much easier tomanufacture the cam surface 56 within closer tolerances than it is tomaintain close tolerances between the outer surface of the housing 62which forms the seating for the switch unit 10. It is even harder tomaintain close tolerances between the cam surface and the switchcontacts within the unit 10.

In accordance with the present invention the transmission switch unit 10is provided with means, generally designated 40, for automaticallyadjusting and fixing the position of the plunger 18 for the making andbreaking of the electrical contacts in response to the initialarrangement of the switch unit 10 into its seating in the housing 62 andof the activating member, cam 54, into its predetermined high or parkposition. This automatic self-adjusting and fixing of the plunger-allowsfor greater range of tolerance build-up between the cam surface 56 andthe electrical contacts made and broken by the ring 30. Intheillustrated construction, these means 40 preferably include an axialcylindrical bore 42 in the spool 26, an axial cylinder extension 18A ofthe plunger 18 for entering into the bore 42, and locking means 44 inthe form of a slit sleeve lock washer, as may be better seen in FlG.'-4.The means 40 provide for telescopic movement of the plunger 18 into thespool 26 in response to a relative large force, i.e. a force largeenough to overcome the lock washer 44.

Referring to FIG. 4 it can be seen that the lock washer 44 has anoutstanding rim portion 44R at one end which forms a shoulder surface448 for bearing against the front face 26F of the spool 26 (FIGS. 2 and3). A hollow cylindrical sleeve portion 44C extends from the rim 44R forseating in the enlarged bore 42 and which, in use, extends coaxiallywith the bore 42 and the plunger stern segment 18A from the frontsurface of the spool 26 to a position deep within the spool 26. Althoughthe fit between the washer 44 and the bore 42 need not be'tight as thespring 36 will at all times urge the spool 26 against the lock washersrim 44R, for ease in assembly of the switch unit 10, a pair ofoutstanding side flanges 44F may be provided. The rim 44R and sleeve 44Care longitudinally split at 448?.

The unstressed diameter of the opening in .the rim is somewhat smallerthan that of thestem portion 18A so as to resiliently spread to aid incaptivating that portion 18A as it is inserted through the lock washer44.

It should also be noted that, if desired, the relationship between theactuating member predetermined or high position and the switch contactsmay be other than that depicted in the specific embodiment without Thesleeve of the lock washer 44 has a plurality of 5 departing from theprinciples of the present invention.

longitudinal slits 44L formed therein which slits 44L divide the sleeveinto sections MP. The end tips 44E of these sections 44P are preferablybent or curved inward. When the stem 18A of the plunger 18 is insertedinto the lock washer 44 it not only spreads the washer 44 but alsocauses the rearward ends 44E of the sleeve sections 44? to beresiliently spread apart to bear tightly against the outer surface ofthe stem 18A.

The operation of the present invention is .best shown in FIGS. 5 through8 which illustrate the various stages of the assembly of the switch unit10 into a transmission housing 60.

As shown in FIG. 5, before mounting of the switch unit 10, the stem 18extends forward a great deal further than the position it adopts in use.As shown, a marking groove 18G is formed therein to indicate thisextended or outwardly telescoped position.

.The first step in assembly is to place the transmission in park" sothat cam 54 is in a predetermined position with the highest or mostprotruding surface 59 opposite the opening 64. (Of course, if neutral"is designed to allow starting, it presents the same cam height and couldthen also be employed in aligning the switch unit 10.)

With this orientation the unit 10 is threadably advanced into theopening, as shown in FIG. 5. As the unit 10 continues to be threadablyadvanced, the forward tip of the plunger 18 makes contact with thesurface 59 and is moved, relative to the body 12, backwards. The spool26 is moved thereby backwards as shown in FIG. 6. The spool 26 is movedfurther backwards (relative to the body 12) as the unit 10 is threadablyadvanced until its surface 26Y makes contact with the surface 20X asshown in FIG. 7.

As the unit 10 is further threadably advanced the plunger 18 movesfurther into the spool 26, through the locking washing 44. Thiscontinues until the shoulder 16 meets the housing outer surface 62, asshown in -FIG.'8. The switch unit 10 is now secured in place andproperly aligned.

As should now be apparent a new. and improved self adjustingstart-inhibitor switch unit for motor vehicles having automatictransmissions has been described in which the self-adjusting is achievedonce-and-for-all upon assembly and further or continuing adjustmentsneed not be made despite the extremes of tolerance build-up in anindividual case. The switch unit described has the advantages ofproviding only a single moving unit, made up of the plunger 18, thespool 26 and the lock washer 44 for closing and opening contacts andalso for those contacts to be easily sealed from the environment of theplunger acting cam.

The invention provides a switch unit that is both economical tomanufacture, easy to mount and provides consistent behavior tolerancebuild-ups between different environments of mounting.

Although of primary utility when used in conjunction with vehiclesequipped with automatic transmissions, the switch may also find use invehicles equipped with manual transmissions for the control, forexample, of only the back-up lamps.

For example, the actuating cam may be made with the reverse" or a driveposition being the highest surface and the switch contacts axially makeand break positions reordered to accommodate.

While particular embodiments of the invention have been shown anddescribed, it will be obviou's'to' those skilled in the art that changesand modifications may be made without departing from the invention inits broader aspects and, therefore, the aim in the appended claims is tocover all such changes and modifications as fall within the true spiritand scope of the invention.

What is claimed is:

1. In a transmission electrical switch unit adapted to be activated inresponse to transmission control members, said switch unit being of thetype having a plunger that is axially displaced from and returned to aposition in response to movement of an activating member to and from apredetermined position to thereby break and make an electrical contact,and which unit is adapted to be affixed in a seating adjacentto saidactivating member, the improvement of having provision within theswitchunit for adjusting and fixing the axial spacial relationship of theplunger with respect to the contact, in response to the initialarrangement of the switch unit in said seating and of said activatingmember in the predetermined position, into one axial spacial relation sothat the contact and plunger are thereafter maintained during normal userigidly coupled together.

2. The improvement, as defined in claim 1, in a transmission electricalswitch unit of the type there set out, wherein:

said adjusting means includes an internally located shaft (18A) andsleeve (26') arranged for inverse telescopic movement therewith duringthe affixing of said unit into its seating.

3. The improvement, as defined in claim 2, in a transmission electricalswitch unit of the type there set out,

wherein:

said adjusting meansincludes locking means (44) for locking to one ofsaid shaft and said sleeve whereby determining that relative positionduring normal operation of the switch unit, but allows inversetelescopic motion therebetween for forces exceeding those encounteredduring normal operation.

4. The improvement, as defined in claim 3, in a transmission electricalswitch unit of the type there set out, wherein:

said locking means is a locking washer.

5. A start inhibitor switch unit for use in motor vehicles equipped withtransmissions comprising:

a housing having a threaded portion for mounting the unit to thevehicle;

a plunger (18) carried in said housing so as to be movable inresponse'to an activating device of said vehicle;

means, mounted on said housing, including at least one electricalterminal, for defining a breakable electric current path, said meansfurther including a movable circuit breaking and making member (26); andself-adjusting means (40) coupling together said circuit breaking andmaking member and said plunger for adjustably locking said circuitbreaking and making member and said plunger together, said locking meansbeing made so as to, in response to the initial mounting of the unitinto the vehicle, allow for the spacing between said member and saidplunger to be adjusted so that said member is at a predeterminedoperating position in relation to the actuating means.

6. A transmission electrical switch unit adapted to be fixed to aseating adjacent an activating member and to be activated in response totransmission control members, said switch unit comprising a plungerwhich is axi- 7 said shaft and/or said sleeve, whereby determining theirA relative position during normal operation of the switch unit, butallows telescopic motion therebetween for forces exceeding thoseencountered during normal operation.

9. A switch unit according to claim 8, wherein said locking means is alocking washer.

ally displaced from and returned to a position in 10. A switch unitaccording to claim 5, wherein the locking means comprises an axiallysplit spring sleeve surrounding said plunger and engaging in a bore insaid breaking and making member, said sleeve normally locking into saidplunger but being slidable thereon when extra force is applied to saidplunger during mounting of the unit on a vehicle.

11. A switch unit according to claim 10, wherein the breaking and makingmember comprises a spool of insulating material having a circumferentialconducting ring selectively engageable with' a resilient contactconnected to the or each terminal.

1. In a transmission electrical switch unit adapted to be activated inresponse to transmission control members, said switch unit being of thetype having a plunger that is axially displaced from and returned to aposition in response to movement of an activating member to and from apredetermined position to thereby break and make an electrical contact,and which unit is adapted to be affixed in a seating adjacent to saidactivating member, the improvement of having provision within the switchunit for adjusting and fixing the axial spacial relationship of theplunger with respect to the contact, in response to the initialarrangement of the switch unit in said seating and of said activatingmember in the predetermined position, into one axial spacial relation sothat the contact and plunger are thereafter maintained during normal userigidly coupled togetHer.
 2. The improvement, as defined in claim 1, ina transmission electrical switch unit of the type there set out,wherein: said adjusting means includes an internally located shaft (18A)and sleeve (26) arranged for inverse telescopic movement therewithduring the affixing of said unit into its seating.
 3. The improvement,as defined in claim 2, in a transmission electrical switch unit of thetype there set out, wherein: said adjusting means includes locking means(44) for locking to one of said shaft and said sleeve wherebydetermining that relative position during normal operation of the switchunit, but allows inverse telescopic motion therebetween for forcesexceeding those encountered during normal operation.
 4. The improvement,as defined in claim 3, in a transmission electrical switch unit of thetype there set out, wherein: said locking means is a locking washer. 5.A start inhibitor switch unit for use in motor vehicles equipped withtransmissions comprising: a housing having a threaded portion formounting the unit to the vehicle; a plunger (18) carried in said housingso as to be movable in response to an activating device of said vehicle;means, mounted on said housing, including at least one electricalterminal, for defining a breakable electric current path, said meansfurther including a movable circuit breaking and making member (26); andself-adjusting means (40) coupling together said circuit breaking andmaking member and said plunger for adjustably locking said circuitbreaking and making member and said plunger together, said locking meansbeing made so as to, in response to the initial mounting of the unitinto the vehicle, allow for the spacing between said member and saidplunger to be adjusted so that said member is at a predeterminedoperating position in relation to the actuating means.
 6. A transmissionelectrical switch unit adapted to be fixed to a seating adjacent anactivating member and to be activated in response to transmissioncontrol members, said switch unit comprising a plunger which is axiallydisplaced from and returned to a position in response to movement of anactivating member to and from a predetermined position to break and makean electrical contact, and means within the switch unit for adjustingthe axial spacial relationship of the plunger with respect to thecontact in response to the initial arrangement of the switch unit insaid seating and of said activating member in the predeterminedposition, and for fixing said plunger and contact in that axial spacialrelationship so that they remain in that relationship during normal usethereafter.
 7. A switch unit according to claim 6, wherein adjustingmeans includes an internally located shaft and a sleeve arranged fortelescopic movement therewith during the fixing of said unit into itsseating.
 8. A switch unit according to claim 6, wherein said adjustingmeans includes locking means for locking to said shaft and/or saidsleeve, whereby determining their relative position during normaloperation of the switch unit, but allows telescopic motion therebetweenfor forces exceeding those encountered during normal operation.
 9. Aswitch unit according to claim 8, wherein said locking means is alocking washer.
 10. A switch unit according to claim 5, wherein thelocking means comprises an axially split spring sleeve surrounding saidplunger and engaging in a bore in said breaking and making member, saidsleeve normally locking into said plunger but being slidable thereonwhen extra force is applied to said plunger during mounting of the uniton a vehicle.
 11. A switch unit according to claim 10, wherein thebreaking and making member comprises a spool of insulating materialhaving a circumferential conducting ring selectively engageable with aresilient contact connected to the or each terminal.